考虑倾角影响的扩大头锚杆极限抗拔力  

Ultimate pullout capacity of end-expanded ground anchors considering inclined angle effect

作　　者：江建洪 曾庆义 马健 JIANG Jianhong;ZENG Qingyi;MA Jian(School of Rail Transportation,Soochow University,Suzhou 215131,Jiangsu,China;Shenzhen Julian Anchor Technology Co.,Ltd.,Shenzhen 518034,Guangdong,China;SGIDI Engineering Consulting(Group)Co.,Ltd.,Shanghai 200093,China)

机构地区：[1]苏州大学轨道交通学院,江苏苏州215131 [2]深圳钜联锚杆技术有限公司,广东深圳518034 [3]上海勘察设计研究院(集团)有限公司,上海200093

出　　处：《哈尔滨工业大学学报》2022年第2期154-161,共8页Journal of Harbin Institute of Technology

基　　金：国家自然科学基金(51308364)。

摘　　要：扩大头锚杆因其对土层的选择要求而常常具有一定的锚杆倾角,而目前工程实践中未充分考虑该倾角对锚杆抗拔力的影响。为此,在原有研究基础上,采用莫尔-库伦强度理论推导考虑倾角影响的扩大头锚杆极限端压力和抗拔力的表达式,从力学机制层面解释土体黏聚力、内摩擦角和扩大头埋深对极限端压力随锚杆倾角变化的影响。结果表明:极限端压力在静止土压力系数不大于1时随锚杆倾角的增大而减小,而在静止土压力系数大于1时随锚杆倾角的增大而增大;黏聚力因其各向同性性质使得极限端压力随锚杆倾角的变化不敏感,而内摩擦角和扩大头埋深因各向异性因素使得极限端压力呈现复杂变化;对于静止土压力系数不大于1的常规土体,目前工程规范中将倾斜锚杆的抗拔力取值为完全水平锚杆的抗拔力,或偏于不安全。相关公式和规律可为采用扩大头锚杆的锚固工程设计提供参考。Usually there is an inclined installation angle for an end-expanded ground anchor due to the requirement for soil layer selection,yet its influence on the pullout capacity of the ground anchor is not fully considered in the current practice.Based on the previous study and adopting the Mohr-Coulomb strength theory,expressions for the ultimate earth pressure on the expanded end and its pullout capacity were derived for an end-expanded ground anchor considering the inclined angle effect,and the relationship between the ultimate earth pressure on the expanded end and the inclined angle was explained under the conditions of different soil cohesions,angles of internal friction,and burial depths of the expanded end according to the basic mechanical mechanism.Research results show that the ultimate earth pressure on the expanded end decreased with increasing inclined angle in soil when the coefficient of earth pressure at rest was less than or equal to 1,and it increased with increasing inclined angle in soil when the coefficient of earth pressure at rest was larger than 1.The cohesion made the ultimate earth pressure on the expanded end less sensitive to the inclined angle due to its isotropic nature,while the angle of the internal friction and the burial depth of the expanded end made the ultimate earth pressure on the expanded end change in a complex way due to their anisotropic nature.For regular soils with coefficient of earth pressure at rest less than or equal to 1,the current practice in the specification that the pullout capacity of an inclined anchor practically adopts the one of the corresponding horizontal anchor may lead to unsafe design.The related expressions and rules can provide references for the design of anchoring engineering with end-expanded ground anchors.

关 键 词：扩大头锚杆 锚杆倾角 端压力 抗拔力 黏聚力 内摩擦角 

分 类 号：TU473[建筑科学—结构工程]